Wear rates of regular and tempered composites

Objectives: One of the reasons for using composite inlays is that restorations can be tempered. Composites tempered with heat and light have, at least initially, an enhanced degree of cure which, it is claimed, improves their physical properties, including wear resistance. The aim of this study was to compare the wear rates of a selection of composites in their regular and tempered conditions. Methods: Two hybrid composites (Brilliant Dentin, Coltène; Occlusin, ICI) and a microfilled material (Heliomolar, Ivoclar-Vivadent) were chosen to provide a variety of filler particle and resin systems. Regular composites were cured normally with light while tempered composites were given an additional 8 min secondary cure at 120 °C in the Coltène DI500 heat and light oven. Specimens of an amalgam (Dispersalloy, Johnson & Johnson) and a heat/pressure cured composite (Isosit, Ivoclar-Vivadent) were used for comparison. The specimens were stored for either 7 days or 1 year to determine if prolonged water storage affected wear rate. Wear testing was carried out in a two-body wear machine using a steatite abrader as an enamel substitute. ANOVA was used to test the effects on wear rate of tempering, storage time and type of material. Results: Significant differences were found in wear rate between materials (p < 0.001), but not for tempering or prolonged storage time. Conclusion: These findings agree with clinical studies which have shown that tempering has little or no influence on the occlusal wear of composite inlays.